VI. EMF Issues

During the proceeding, there was a great deal of public interest and concern regarding potential health effects from EMF exposure due to power lines.28 Several intervenors along the proposed Jefferson-Martin route ask that the Commission choose a route that reduces or eliminates the risks associated with EMF exposure, particularly to high priority groups including schools, day care centers, and residences.

The FEIR provided extensive information regarding EMFs. However, it did not consider EMF exposure in its determination of the environmentally superior routes on the basis that there is no agreement among scientists that EMF creates a potential health risk and there are no defined or adopted CEQA standards for defining health risk from EMF. As noted in D.90-09-059, § 1002 provides us with responsibility independent of CEQA to include environmental influences and community values in our consideration of a request for a CPCN. The intervening parties have made clear that the potential for health effects due to EMF from this project is of grave concern to the affected communities. Pursuant to § 1002, we consider EMF issues as we determine which project alternative should be authorized.

In 1991, the Commission initiated an investigation, I.91-01-012, into EMFs associated with electric power facilities. In D.93-11-013 in that proceeding, we found that, while EMF studies available at that time did not conclude that an EMF health hazard exists, it was appropriate to adopt several EMF policies and programs because of public concern and scientific uncertainty. We required that utilities undertake no-cost EMF mitigation measures and that they implement low-cost mitigation measures to the extent approved through a project's certification process.29 We defined "low-cost" to be in the range of 4% of the total project cost but specified that this 4% benchmark is not an absolute cap. We found that, to be implemented, a mitigation measure should achieve some noticeable reduction in EMF but declined to adopt a specific goal for EMF reduction. We instructed that workshops be held and that the utilities develop EMF design guidelines for new transmission facilities. We adopted several EMF measurement, education, and research programs and chose the California Department of Health Services (DHS) to manage the education and research programs.

A. Scientific Research Regarding EMF

The FEIR and the parties in this proceeding reported the results of a number of scientific studies related to EMF. Intervenors along possible Jefferson-Martin routes cite numerous scientific studies that, in their view, provide compelling reason for concern about the potential health risks associated with EMFs from power lines. They maintain that numerous studies have demonstrated an association between EMFs and serious diseases, even if causal links have not been established. San Mateo asserts that anxiety and lack of certainty about the safety of EMF exposure, by themselves, create a public health issue, citing potential stress-related health effects. These intervenors recommend that, in light of the studies and continued uncertainty, the Commission choose a route alternative that reduces or eliminates the risks associated with EMF exposure. 280 Citizens asks that the Commission adopt a standard that transmission-related EMF exposure from the combined effect of the existing 60 kV and new 230 kV lines should not exceed 1 mG at residential property boundaries. It asks that the Commission route the southern segment away from residential areas and schools where feasible and, where that is not feasible, require that the lines be undergrounded in a manner that achieves this standard.

PG&E responds that there is no scientific basis that EMF exposure causes adverse health effects. Its expert witness testified that, despite decades of scientific inquiry, there remains insufficient scientific evidence to conclude that EMF causes any adverse health effects. PG&E asserts that the state of scientific knowledge remains where it was when the Commission adopted the precautionary approach of requiring no-cost and low-cost mitigation but declined to adopt a numerical limit. PG&E maintains that there is still no scientific basis to set any health-based EMF standard and concludes that there is no reason to depart from the Commission's 1993 no-cost, low-cost EMF reduction policy. CARE agrees with PG&E that EMF is not a serious consideration that would affect the balance of issues in this case.

The state of scientific knowledge has advanced in the period since we issued D.93-11-013. While causation has not been proved definitively, several studies in the intervening years have found correlations that we cannot responsibly ignore. In assessing the numerous scientific EMF studies, we find DHS's comprehensive review of existing EMF studies undertaken at the Commission's direction in I.91-01-012 to be of particular value. The DHS study reviewed several of the other scientific studies cited in this proceeding and thus took those studies' findings into account in its conclusions. Three DHS staff scientists undertook the evaluation and the DHS final report, published in 2002, identified their individual professional judgments regarding EMF risks. Their conclusions include the following:

· All three of the DHS scientists were inclined to believe that EMF exposure can cause some degree of increased risk of childhood leukemia, adult brain cancer, Lou Gehrig's Disease, and miscarriage.

· One scientist was "prone to believe" and two were "close to the dividing line between believing or not believing" that EMFs cause some degree of increased risk for adult leukemia.

· All three scientists had judgments that were "close to the dividing line between believing and not believing" that EMFs cause some degree of increased risk of suicide.

· They were all inclined to believe that EMF exposure does not cause an increased risk of breast cancer, heart disease, Alzheimer's Disease, depression, or symptoms attributed by some to a sensitivity to EMFs.

· They all strongly believed that EMFs do not increase the risk of birth defects or low birth weight, and that EMFs are not universal carcinogens since a number of cancer types are not associated with EMF exposure.

While there is no definitive proof at this point, we must proceed with the knowledge that EMF exposure may increase the risk of certain health effects. In routing the Jefferson-Martin project and considering PG&E's EMF management plan for the project, it is entirely appropriate and prudent for us to consider the EMF levels that would be created by the various possible routings and configurations of the project. At the same time, we find that the state of scientific knowledge has not advanced to the point to support adoption of the numerical EMF exposure standard that 280 Citizens proposes.

B. EMF along Routes under Consideration

Several intervenors along the proposed Jefferson-Martin routes ask that, if a Jefferson-Martin project is authorized, the Commission choose a route that reduces or eliminates the risks associated with EMF exposure.

The overhead southern segment of PG&E's Proposed Project would be located in watershed lands and would pass next to residential developments in the unincorporated San Mateo County area known as The Highlands, the Town of Hillsborough, and the City of Burlingame. It would pass the Hillcrest Juvenile Detention Home in San Mateo (over 125 feet east of the alignment) and Nueva School in the Town of Hillsborough on the opposite side of I-280 from the route.

The underground southern alternative Route Option 1B would be located partly in watershed lands but would traverse residential areas along Skyline Boulevard, Trousdale Drive and El Camino Real. It would pass Franklin Elementary School, set back about 75 feet from Trousdale Drive, and Mills-Peninsula Hospital, with buildings set back about 275 feet from Trousdale Drive.

The majority of the underground northern segment of the Proposed Project would pass through commercial areas. However, there are several residential areas along this portion of the Proposed Project, including along San Bruno Avenue, Huntington Avenue, the BART right of way, Lawndale Drive, Hillside Boulevard, Hoffman Street, and Orange Street. Route Option 4B would avoid the residential areas on Hoffman and Orange, but would pass other residences on Hillside Boulevard and East Market Street. The underground segment would pass Kaiser Permanente Medical Center and also several schools:

· Herman Tot Lot day care center (San Bruno)

· South San Francisco High School (South San Francisco, with school buildings set back 750 feet from the alignment)

· Los Cerritos Elementary School (South San Francisco)

· Boys and Girls Club (South San Francisco, 11 feet from the line)

· El Camino High School (South San Francisco, with school buildings 50 feet from the alignment)

· Susan B. Anthony High School (Route Options 4A and 4B, Daly City, with school buildings over 100 feet from the alignment)

· John F. Kennedy Elementary School (Daly City, with a school building 40 feet from the alignment (Ex. 13, Att. 205 at E-20))

The Collocation Alternative would pass a small number of residences on San Bruno Avenue and would be near residences along a short segment on Seventh Street. If either the Sneath Lane alternative or Mitigation Measure T-9a is implemented to avoid the grade separation project at the intersection of San Bruno Avenue and Huntington Avenue, these residential areas would be avoided but residences along Tanforan Avenue would be passed.

PG&E calculated the expected 2006 magnetic fields along the portions of the Proposed Project and AUA routes that would pass through residential and commercial areas. PG&E performed the calculations for four load scenarios: low loading (load is less 5% of the year), medium loading (load is less 50% of the year), high loading (load is less 95% of the year), and normal summer peak (highest expected loading of the year). In PG&E's view, the "medium" loading levels are the most apt for evaluation purposes. We agree, because magnetic field levels at medium loading conditions are the best indication in the record of what year-round EMF exposure levels may be.

PG&E reported magnetic field levels for buildings along the routes, with building locations determined from aerial photographs. PG&E cautioned that many buildings may be further from the transmission line than it assumed, due to roof overhangs or other factors that cause inaccuracies in interpreting the aerial photos.

280 Citizens submitted an independent evaluation of magnetic field levels in the southern segment for several scenarios, including the existing overhead 60 kV circuits alone, PG&E's proposed route with a 60 kV circuit and the new 230 kV circuit collocated overhead, PG&E's Route Option 1B for the 230 kV circuit and continued operation of the existing 60 kV line, and 280 Citizens' MPUA alternative with the 230 kV and 60 kV lines collocated underground.

Magnetic field exposures from the Jefferson-Martin project would depend on the distance from the line. For overhead configurations, magnetic field exposures depend on tower placement and height in addition to horizontal distance from the line, e.g., field exposure would be lower near a tower because the line is higher in the air than it is near the mid-span.

PG&E provided two sets of magnetic field exposure data along the southern overhead portion of the proposed project: (1) for the existing double-circuit 60 kV line operating by itself and (2) if the Proposed Project is built, i.e., for rebuilt towers carrying the new 230 kV circuit and a single 60 kV circuit. PG&E provided only normal summer peak loading data for the existing 60 kV line, but provided data for all four loading scenarios for the Proposed Project. Thus, we can compare peak magnetic field estimates, but not exposures during medium loading conditions, before and after the project is built.

Along the above-ground segment of the Proposed Project, the closest residential building is approximately 25 feet from the existing 60 kV line; 42 residential buildings are within 100 feet of the line. PG&E reports that during summer peak loading conditions, magnetic field exposure levels due to the existing line would be less than 1 mG for most residences along the route, between 1 mG and 3 mG along Lexington Avenue, and as high as 5.3 mG for homes along Skyline Boulevard. For the combined 60 kV and 230 kV circuits, the magnetic field levels during summer peak conditions would range up to 6.5 mG (4.5 mG during medium loading conditions) along Lexington Avenue and as high as 22.5 mG (15.5 mG during medium loading conditions) further north until the line crosses to the west of I-280 at mile point 10.7.

The PUA would reduce magnetic field exposures significantly compared to the Proposed Project, because it would underground the combined 230 kV and 60 kV lines near some residences and re-route the rebuilt line away from other residences. The MPUA would reduce magnetic field exposure further, because it would re-route the underground portion of the PUA to the west such that peak magnetic field levels at property boundaries would not exceed 1 mG.

PG&E provided magnetic field estimates for the underground portion of the Proposed Project and for Route Option 1B. Assuming a uniform duct bank depth, magnetic field levels along an underground installation would depend solely on distance from the line. The following table, compiled from PG&E's magnetic field studies,30 shows the types and locations of buildings that are at specified distances from the underground line and the associated magnetic field levels under medium loading conditions. The BART right of way, Hoffman Street, Orange Street, San Bruno Avenue, and Hillside Boulevard are on the northern underground segment of the Proposed Project. Skyline Boulevard, Trousdale Avenue, and El Camino Real are on Route Option 1B, the underground southern alternative. This table does not include information for locations more than 50 feet from the underground line, for which magnetic field exposure would be less than 1.3 mG under medium loading conditions.

Table 3

Magnetic Field Exposure

Route Option 1B and Underground Northern Portion of Proposed Project

Medium Loading Conditions

Distance from Magnetic

line (feet) field (mG) Building type and location

9 23.3 Commercial-BART right of way

10 20.7 Commercial--BART

11 18.4 Boys & Girls Club--BART

12 16.4 Commercial--BART

18 8.8 Multi-family residential-BART*

20 7.4 Residential--Hoffman

21 6.8 Residential--Hoffman

22 6.3 Commercial--El Camino Real, BART

25 5.0 Residential--Hoffman and Orange,

Commercial--BART

26 4.6 Commercial--Hillside, San Bruno,

El Camino Real and Trousdale

27 4.3 Commercial--San Bruno

28 4.0 Commercial--San Bruno

29 3.8 Residential-Orange, El Camino Real

30 3.6 Residential-Hoffman, Orange, Trousdale

Commercial-Hoffman, San Bruno,

El Camino Real, Trousdale

31 3.3 Residential-Trousdale, Skyline

32 3.2 Residential-Trousdale, Skyline

33 3.0 Residential-Trousdale

Commercial-BART, Skyline

34 2.8 Residential and commercial--Trousdale

35 2.7 Commercial-Trousdale, Skyline

36 2.5 various

39 2.2 various

40 2.1 various

45 1.6 various

50 1.3 various

*PG&E reports living units are on the second floor, with magnetic fields of 5.3 mG.

Magnetic field exposure for buildings along Route Option 4B would probably be less than along Hoffman and Orange Streets because Hillside Boulevard and East Market Street are wider and thus may allow the line to be placed further from the sidewalks. The record does not contain magnetic field calculations for the Collocation Alternative.

This recitation of the EMF calculations is useful to identify what portions of the route alternatives would create the highest exposures to magnetic fields. We recognize intervenors' concerns that this data does not reflect exposure levels in yards or other outdoor locations that may be closer to the line. However, the information is useful as an indication of exposures where residents would spend their sleeping and much of their waking hours while at home.

The highest reported magnetic fields would occur along the BART right of way in the northern segment of PG&E's Proposed Project. A few residences along the southern overhead segment of the Proposed Project exhibit exposure levels approaching those reported along portions of the BART right of way. Other relatively high exposure levels would occur on Hoffman and Orange. The highest calculated residential exposure on the southern underground Route Option 1B is less than one quarter of the highest calculated residential exposure on the northern route.

We take this information regarding magnetic field levels into account in adopting EMF mitigation measures in Section VI.C and as we weigh a variety of environmental and other factors in assessing the routes in Section VII.

PG&E maintains that magnetic field levels from the Proposed Project and the AUA are low and within the range of magnetic fields commonly encountered in everyday life. PG&E reported a study of everyday levels of magnetic field exposure, which indicated a 24-hour average to be 1.25 mG. Of the people studied, 43.6% had 24-hour average exposures of 1 mG or more, 14.3% had a 24-hour average exposure over 2 mG, and 6.35% had an average exposure over 3 mG. PG&E also reported on magnetic field levels experienced locally, including in Burlingame, obtained by a PG&E witness walking around various streets, visiting commercial and governmental buildings, and riding mass transit. The PG&E witness found an average magnetic field of 11.4 mG during the two- or three-hour walk.

The FEIR describes research indicating that ambient magnetic fields in most residences and other buildings average approximately 1 mG. The FEIR also reports that typical magnetic fields emitted by appliances include the following (at a distance of 12 inches):

Magnetic

Appliance Field (mG)

Electric range 3 to 30

Refrigerator 0.3 to 3

Clothes washer 2 to 30

Coffee maker 0.8 to 1

Vacuum cleaner 20 to 200

Color TV 9 to 20

Flourescent fixture 2 to 40

In evaluating this data, we note that the level of EMF exposure attenuates with distance much more rapidly from appliances than from power lines, and that many appliances are operated only intermittently. We find the evidence elicited by the tour of Burlingame to be of limited usefulness since it was clear that the witness visited areas known to have relatively high EMF levels, e.g., check-out areas of the local library. It is clear that, for portions of the routes under consideration, residents would be subjected to cumulative magnetic field exposures far in excess of what they would be likely to receive from other sources.

C. EMF Management Plan for the Jefferson-Martin Project

PG&E implemented EMF design guidelines in 1994 following workshops as required by D.93-11-013. PG&E's EMF design guidelines describe the no-cost and low-cost measures that it undertakes as follows:

No cost measures are those steps taken in the design stage, including changes in standard practices, which will not increase the project cost but will reduce the magnetic field strength.

Low cost measures are those steps that will cost about 4% or less of the total project cost and will reduce the magnetic field strength in an area (e.g., by a school, near residences, etc.) by approximately 15% or more at the edge of the right of way. The total project cost is defined as all costs associated with the siting, design and construction of those specific new or upgraded transmission, substation, or distribution project facilities. The total project cost figure used, as a basis for low cost determination, is only that particular component of the project being evaluated for magnetic field reduction steps. As an example, when a substation and a transmission line are being designed, 4% of the total cost for the transmission line will be considered for magnetic field reduction from the line and 4% of the total substation cost will be considered for reduction from the substation. ...

PG&E's EMF design guidelines establish a prioritization of areas for low-cost EMF reduction, based on its perception of public concern. Beginning with the groups of highest priority, PG&E's prioritization of areas for application of EMF mitigation measures is as follows:

1. Schools, licensed day care

2. Residential

3. Commercial/industrial (includes hospitals)

4. Recreational

5. Agricultural, rural

6. Undeveloped land, zoned for residential

7. Undeveloped land, zoned for commercial/industrial

8. Unpopulated, forested, government owned land

The guidelines state that unless all areas within a priority group can receive equivalent treatment, no single area in that priority group will receive low-cost measures, with "equivalent" defined as the application of some type of low-cost measure to all areas in a priority group.

PG&E prepared a preliminary EMF management plan for the Jefferson-Martin project. In this plan, PG&E proposes arranging the phases of the overhead portion of the line to reduce magnetic field levels as a no-cost mitigation measure. That document states that there are no feasible no-cost mitigation measures for the underground portion of the project. PG&E reports that, with no-cost design measures, the base case magnetic field level during normal summer peak loading conditions would be 30.6 mG at one edge of the 100-foot right of way for the overhead line (the 230 kV circuit and one 60 kV circuit) and 15.0 mG at each edge of the 30-foot right of way for the underground portion of the 230 kV line.

PG&E's preliminary EMF management plan established 4% EMF budget benchmarks separately for each component of the Proposed Project. As low-cost mitigation near schools, the plan proposes to raise the height of towers by 20 feet or to lower the depth of underground conductors by 5 feet. This would lower the peak loading magnetic field at the edge of the right of way to 17.3 mG for the overhead rebuilt line (a 43.5% reduction) and to 11 mG for the underground 230 kV line (a 26.7% reduction). The preliminary plan does not propose to undertake any EMF mitigation measures in residential areas, however, since the total cost of these measures for all residential areas, in combination with school mitigation measures, would exceed 4% of the estimated cost of the transmission line portion of the project.

The County of San Mateo is concerned that, under PG&E's EMF design guidelines and proposed mitigation plan for Jefferson-Martin, EMF mitigation would be limited and would reduce EMF in only a few areas. San Mateo points to PG&E's planned 4% limit and its policy to not provide low-cost mitigation to a priority group of customers unless all areas within the priority group can receive equal treatment.

During the evidentiary hearing, the ALJ questioned PG&E about possible changes to its EMF management plan for Jefferson-Martin and PG&E provided a written response (Exhibit 164). PG&E states first that, rather than creating separate 4% benchmarks for the transmission line and substation portions of the Jefferson-Martin project, it is willing to have a single EMF mitigation budget based on the total estimated costs of the entire project.

Second, PG&E responded to ALJ inquiries about PG&E's policy that, if it cannot provide low-cost EMF mitigation to all customers within a priority class and stay within its EMF mitigation budget, PG&E would not provide low-cost EMF mitigation to any customer within the class. PG&E states that it has concerns about any mitigation measure that does not require equal treatment within a priority class and asks that, if such an approach is adopted, the Commission provide clear direction on how to allocate the funds among land uses within the same priority class.

With that caveat, PG&E describes in Exhibit 164 ways in which EMF mitigation could be focused within a priority class. PG&E reports that an option applicable to a project with both overhead and underground segments would be to favor EMF mitigation for overhead lines instead of underground lines, since EMF levels at the edge of the right of way tend to be higher for overhead lines than for underground lines.

PG&E also describes two options for targeted EMF mitigation applicable to underground lines. One option would be to lower the depth of the trench along all portions of the route adjacent to residential areas by an equal amount, with the depth determined by the EMF mitigation budget. A second option would be to provide mitigation based upon distance from the underground cable. For that option, after final design work is complete, PG&E could measure the distance from the planned line location to the nearest residential living unit (for example, a house rather than a garage or shed) on a block, and compare that to other blocks along the route. For blocks with residences closest to the line, the nominal depth of the trench would be lowered to achieve an estimated 15% reduction in magnetic field. This process would continue until the EMF mitigation budget is depleted. PG&E is concerned that this approach would require that line placement for the entire line be determined before any construction commences, contrary to current practice in which the actual location of the line is usually determined shortly before each stretch of the line is installed.

We require several changes to PG&E's preliminary EMF management plan for the Jefferson-Martin project in order to make more effective use of EMF mitigation funds. First, we adopt a single 4% EMF mitigation benchmark for all of the project, as PG&E suggests, rather than allowing the funds to be divided and administered separately for each component of the project.

Because the overhead portion of the route we authorize does not pass any high priority groups, we do not need to address PG&E's proposal in its preliminary EMF Management Plan to mitigate EMF exposure for the Jefferson-Martin project by raising the height of towers by 20 feet in targeted areas. As a general matter, we agree with PG&E's proposed low-cost EMF mitigation measure for underground routes in which it would lower the depth of the underground conductors by 5 feet. Starting with a standard 6-foot deep trench, an additional 5 feet would lower the peak load magnetic field at each edge of a 30 foot right of way by about 26.7%, to about 11 mG. We note that the magnetic field levels during non-peak conditions would be substantially less than this amount, and estimate based on data in Attachment 205 in Exhibit 13 that the magnetic field during medium loading conditions would be about 7.6 mG at each edge of a 30-foot right of way.

The record does not indicate construction costs or the EMF reduction that could be achieved if the trench is lowered more than five feet as an EMF mitigation measure. In an effort to make the most effective use of EMF mitigation funds, we will not require PG&E to lower the trench below a total depth of 11 feet due to EMF mitigation requirements.

PG&E's preliminary EMF management plan for Jefferson-Martin appears to assume that the conductors would be arranged in a vertical configuration in the underground duct bank. However, a triangular configuration would reduce EMF levels significantly. In the EMF calculations in Exhibit 13, PG&E utilizes a triangular configuration. We require that PG&E use a triangular configuration to reduce EMF levels as a no-cost mitigation measure unless there are obstacles or other impediments that would preclude such a configuration.

Modification of line placement is another EMF mitigation measure that may be implemented at no or relatively low cost in many instances. To the extent allowed by the location of existing underground utilities, PG&E may be able to choose line placement within the right of way in a manner that would reduce EMF exposure within buildings along the way. We instruct PG&E to undertake such strategic line placement along the entire route to the extent it can be accommodated at no or minimal cost. By "minimal" cost, we mean typical trenching and duct bank construction costs that may be incurred because the route may not be as direct as otherwise possible if strategic placement were not undertaken. As a general matter, we do not expect PG&E to undertake more extensive steps such as moving existing underground utilities in order to reduce EMF levels through strategic placement. PG&E should use its judgment, however, regarding the extent to which such additional strategic line placement could be undertaken as a low-cost measure.

PG&E reported particularly high magnetic field levels along portions of the BART right of way, as indicated in Table 3. In response to an ALJ inquiry regarding project design along the BART right of way, PG&E explains that the reported EMF levels were based on preliminary determinations of line placement in light of the expected BART tunnel location and other considerations. PG&E reports that the extent to which it would be able to place the transmission line further from the buildings along the right of way would depend upon the actual, as-built location of the BART tunnel, location of the BART right of way property line, surface and subsurface features, and the minimum bend radii in the routing of the line. PG&E commits, however to locate the line at least 34 feet from the edge of residential and commercial buildings along the BART right of way to the extent "safe, feasible, and cost-effective" as part of its EMF mitigation measures. We adopt this additional strategic line placement requirement, not just along the BART right of way but any place along the route where it is feasible to place the line at least 34 feet from residential living units or other buildings where people are expected to spend significant amounts of time. Such placement would reduce magnetic field levels to 3.0 mG at median loads. We do not expect this requirement to be overly expensive, since there appear to be only a few buildings to which it would apply.

In its EMF design guidelines, PG&E employs a criterion that a low-cost EMF reduction measure should reduce EMF by 15% or more, stating that this criterion is not meant to restrict choices of EMF reduction measures but to guide the design engineer on when a selection or combination is appropriate and justified in a given situation. Consistent with D.93-11-013, we agree that this 15% criterion should provide guidance only in choosing low-cost EMF mitigation measures. Because strategic line placement generally would entail minimal costs, at most, PG&E should undertake strategic line placement, including placement of the line at least 34 feet from buildings where feasible, even if the reduction in EMF is less than 15%.

PG&E's preliminary EMF mitigation plan for the Jefferson-Martin project would provide no low-cost EMF mitigation in any residential areas if lowering the trench an additional 5 feet in all residential areas would exceed a 4% EMF mitigation budget. The proposed decision would have required in such circumstances that the trench be lowered by 5 feet in selected residential areas depending on the distance of residential buildings from the line, up to a 4% EMF budget. In comments on the proposed decision, PG&E commits to lower the trench depth by an equal amount less than 5 feet for all residential blocks where a 15% effectiveness test is met, to the extent allowed by a 4% EMF budget.

The prioritized EMF mitigation approach in the proposed decision based on the distance of residential buildings from the line may have practical difficulties as PG&E suggests, although we do not believe them to be insurmountable. It appears that PG&E's proposal to lower the trench uniformly by an amount allowed by a 4% EMF budget would require similarly that the entire route be engineered prior to determining the depth allowed within the budget. Because of these practical difficulties and in recognition of the intense public concern regarding EMF exposure along residential portions of the route, we require that PG&E lower the trench by 5 feet in all residential areas where this would lower magnetic fields by at least 15%. The low-cost EMF mitigation measure that provides deeper undergrounding near schools and other high priority customers applies in addition to the requirements regarding strategic line placement, i.e., there may be locations where the line's alignment would be moved and it would be placed deeper underground. The determination of whether lowering the trench an additional 5 feet would reduce magnetic fields by at least 15% should be based on a comparison to field levels after strategic line placement. We believe that the adopted EMF mitigation requirements provide a reasonable balance of EMF mitigation for the Jefferson-Martin project in light of scientific studies that support legitimate concern regarding potential health effects of EMF exposure.

We adopt a 4% budget for EMF mitigation as a target budget, not a cap. If PG&E exceeds the cost cap we adopt for the Jefferson-Martin project due to EMF mitigation expenses in excess of the adopted target budget for EMF mitigation, it may seek an increase in the cost cap pursuant to § 1005.5(b).

28 Electric fields are created whenever power lines are energized, whereas magnetic fields are created when current flows through the lines. Both electric and magnetic fields attenuate rapidly with distance from the source. Electric fields are effectively shielded by materials such as trees or buildings, whereas magnetic fields are not easily shielded by objects or materials. Therefore, concerns regarding potential power line EMF health effects arise primarily due to exposure to magnetic fields.

29 The Commission's no-cost and low-cost EMF mitigation requirements were incorporated into G.O. 131-D.30 Some information regarding buildings along the BART right of way was obtained from Exhibit 172.